Typically, a filter cartridge is fixed across the interior of a gas duct so that particulate materials are removed from the gas stream flowing through the interior of each of the filter pockets. When it becomes necessary to replace the filter media in the filter cartridge, the entire cartridge is removed and thrown away and a new cartridge installed in its place.
A common type of air filter referred to as a pocket filter cartridge generally includes a plurality of relatively flat wedge-shaped filter bags fastened to a common mounting frame so that the cartridge includes a series of filter pockets suspended from the frame in adjacent side-by-side relation and resembling a stack of books or an accordion.
Pocket filter assemblies having at least one and typically a plurality of filter bags having an open end attaching to a rectangular flat sub-frame fastened inside the open end of the bag. The sub-frames are fastened together, side by side, and then the sub-frame and bag assembly is supported by a filter frame header wherein the sub-frame is inserted into an inward facing channel of a corresponding sized and shaped main header frame. The header frame is made from a longitudinal channel having three miters spaced out along the channel and a fourth miter at one end. The three miters are bent at right angles with the U-channel facing inward.
U.S. Pat. No. 4,356,011 incorporated by reference herein in its entirety teaches a typical pocket filter assembly. A pocket filter cartridge for removing solid particulate from a dirty gas stream including a plurality of sheath-like filter bags suspended from a common header assembly in side-by-side relation. Each of the filter bags includes a plurality of alternating rows of filamentary stays or span stitching spaced across the width of the bag and extending generally parallel to one another along its length so that upon inflation of the bag by the dirty gas stream during use, the stays shape the bag into a plurality of adjacent tube-like sections opening into one another within the bag. The stays in each row are sized to be of a different length than the stays in the rows adjacent to it to alternately vary the thickness of the bag at the juncture of the tube-like sections formed in the bag.
Typically, one or more of the filter cartridges are secured across the interior of a gas duct so that particulate materials are separated from the gas stream as it flows through the filter media from the interior of each of the filter pockets. When it becomes necessary to replace the filter media in the filter cartridge, the entire cartridge is removed and thrown away and a new cartridge installed in its place.
In filter arrangements of this type, it is necessary to minimize contact between the adjacent filter bags to maintain a uniform flow of gases through the filters as well as to effectively utilize the entire area of the filter media in the filter bags. If this is not done, there can be a substantial pressure loss in the air stream as it flows through the filter cartridge with an attendant increase in the energy required to operate the system. One way of doing this has been to sew the opposing walls of each of the filter bags together so that the filter assumes the shape of a series of separate, adjacent tube-like sections upon its inflation by the gas stream during use. However, while that type of arrangement has proven to be very effective in maintaining separation between the adjacent filter bags, the filter media proximate each of the seams is unavailable for filtering and thus larger and bulkier filters have generally been required. Other arrangements have maintained separation between the adjacent filter bags by shaping them in a tapered or wedge-like configuration. This approach has also proven effective but similarly has required the use of larger filters as well as being relatively difficult to manufacture.
One preferred filter cartridge includes a plurality of relatively flat, sheath-like filter bags suspended from a generally rectangular header assembly in side-by-side relation. Each of the filter bags is assembled from a pair of generally rectangular panels or sheets of flexible filter media sewn together on three sides to form the closed downstream end of the bag and open on the remaining side to form the mouth of the bag which is secured to the header assembly. The filter bag includes a plurality of alternating rows of filamentary stays or span stitching spaced across the width of the bag and extending generally parallel to one another along its length so that upon inflation of the bag by the dirty gas stream during use, the stays shape the bag into a plurality of adjacent tube-like sections opening into one another within the bag. This relatively compact and easily fabricated arrangement effectively maximizes the surface area of the filter media available for filtration while at the same time maintaining sufficient separation between the bags to minimize pressure losses in the gas stream flowing through the filter cartridge.
In this type of filter arrangement, it is necessary to minimize contact between adjacent filter bags to maintain a uniform flow of gases through the filters as well as to effectively utilize the entire area of the filter media in the filter bags. Otherwise, there can be a substantial reduction of air speed through the filter cartridge and an increase in the amount of energy required to propel air through the system. One way of doing this has been to sew the opposing walls of each of the filter bags together to maintain the shape of the filter assembly to resemble tube-like sections when inflated by the gas stream during use. However, while that type of arrangement is very effective in maintaining separation between the adjacent filter bags, the filter media around each of the seams is unavailable for filtering thus reducing filter efficiency. Other arrangements have maintained separation between the adjacent filter bags by shaping them in a tapered or wedge-like configuration. This approach has also proven effective but similarly requires the use of larger filters which are relatively difficult to manufacture.
A conventional header assembly includes a generally rectangular frame and a plurality of elongated rectangular collars, each of which is aligned in the mouth of one of the filter bags and supported within the frame to secure the filter bags to the header assembly. After the collars are positioned in the filter bags, they are secured together by rivets so that the filter media forming the mouth of each of the filter bags is clamped between the adjacent collars as shown in prior art FIGS. 1 and 2. Thereafter, the four legs of the frame are secured about the outermost ends and sides of the collars so that the outermost portions of the filter bags are clamped between the legs of the frame and the collars to complete the assembly.
U.S. Pat. No. 4,356,011 teaches a multi-bag filter cartridge with a main frame holding the wedge shaped bags in a side-by-side arrangement. US Patent Publication No. 201300744636 teaches a filter element for filtering fluids wherein the filter element includes a plurality of wedge shaped sections in a side-by-side arrangement with an outer frame comprising an upper channel member and a lower channel member.